Water in viscous hydrocarbon emulsion combustible fuel for diesel engines and process for making same

ABSTRACT

A combustible fuel for diesel engines and a process for forming same in the form of a water in hydrocarbon emulsion wherein the mean water drop diameter is ≦4 μm with a maximum diameter of ≦10 μm.

BACKGROUND OF THE INVENTION

The present invention relates to a process for utilizing a viscoushydrocarbon as a combustible fuel for diesel engines as well as acombustible fuel product.

It is well known in the art to form hydrocarbon in water emulsionseither from naturally occurring bitumens or residual oils in order tofacilitate the production and/or transportation of these viscoushydrocarbons. Typical processes are disclosed in U.S. Pat. Nos.3,380,531; 3,467,195; 3,519,006; 3,943,954; 4,099,537; 4,108,193;4,239,052; and 4,570,656. In addition to the foregoing, the prior artteaches that hydrocarbon in water emulsions formed from naturallyoccurring bitumens and/or residual oils can be used as combustiblefuels. See for example U.S. Pat. Nos. 4,144,015; 4,378,230; 4,618,348;and British Patent Specification 974,042.

The hydrocarbon in water emulsions discussed above, while useful ascombustible fuels in some power plants, are not suitable for burning indiesel engines, particularly low speed diesel engines. Naturally, itwould be highly desirable to be able to use viscous naturally occurringbitumens and/or residual oils as a combustible fuel for diesel engines.

Accordingly, it is the principal object of the present invention toprovide a process for utilizing a viscous hydrocarbon as a combustiblefuel for diesel engines.

It is a particular object of the present invention to provide a processas aforesaid wherein the viscous hydrocarbon is in the form of anaturally occurring bitumen or residual oil.

It is a further object of the present invention to provide a combustiblefuel for diesel engines in the form of a water in hydrocarbon emulsion.

Further objects and advantages of the present invention will appearhereinbelow.

SUMMARY OF THE INVENTION

The present invention relates to a process for utilizing a viscoushydrocarbon as a combustible fuel for diesel engines as well as acombustible fuel product.

In accordance with the process of the present invention the viscoushydrocarbon is formed as a hydrocarbon in water emulsion in order tofacilitate the production and transportation of the viscous hydrocarbonto the burning site. The hydrocarbon in water emulsion may be preparedby any known process as described in the patents discussed above or asdisclosed in U.S. Pat. Nos. 4,801,304; 4,795,478; 4,834,775; 4,923,483;4,824,439; 4,994,090; 4,776,977; 4,781,819; 4,806,231; and 4,915,819.Additional known processes for forming hydrocarbon in water emulsionsare disclosed in U.S. Pat. Nos. 4,934,398; 4,618,348; 4,666,457;4,684,372; and 4,793,826.

In accordance with the process of the present invention, the hydrocarbonin water emulsion is formed having a hydrocarbon in water ratio of fromabout 60:40 to about 90:10, preferably, 65:35 to 75:25. The hydrocarbonin water emulsion is formed by employing a non-ionic surfactant. Thenon-ionic surfactant is present in the emulsion in an amount of greaterthan or equal to 2000 ppm. The non-ionic surfactant is required to havean ethylene oxide content of greater than or equal to 10 and,preferably, between about 10 to 100. The viscous hydrocarbons usable inthe process of the present invention are those hydrocarbonscharacterized by an API gravity of less than or equal to 16° API and aviscosity of greater than or equal to 100 cPs at 122° F.

The hydrocarbon in water emulsion described above is subjected toinversion by heating the hydrocarbon in water emulsion to an elevatedtemperature and mixing the emulsion at the elevated temperature so as toinvert the emulsion from a hydrocarbon in water emulsion to a water inhydrocarbon emulsion. In accordance with the present invention, it iscritical that the resulting water in hydrocarbon emulsion product have amean water droplet diameter of less than or equal to 4 microns (μm) anda maximum drop diameter of less than or equal to 10 microns (μm). Inorder to obtain a combustible fuel product which may be utilized indiesel engines the drop diameter of the resulting water in hydrocarbonemulsion must be controlled. The diameter of the water droplets iscontrolled by the following factors:

(1) the temperature at which the hydrocarbon in water emulsion is heatedfor inversion,

(2) the concentration of the non-ionic surfactant;

(3) the EO content of the non-ionic surfactant;

(4) the mixing energy employed during the inversion process; and

(5) the ratio of hydrocarbon to water in the original hydrocarbon inwater emulsion.

Specifically, the temperature and mixing energy at which the inversiontakes places increases with an increase in concentration and EO contentof the surfactant and with a decrease in the hydrocarbon content.

Control of the water droplet size and the resulting water in hydrocarbonemulsion is critical in that (1) the presence of water allows for a morecomplete combustion in a diesel engine, (2) small water droplet sizesassist in atomization, and (3) the fuel can be combusted at lowertemperatures which correspondingly result in lower formations of NOXproducts as well as less formation of soot.

Further advantages and features of the present invention will appearhereinbelow from a consideration of the detailed description.

DETAILED DESCRIPTION

The present invention is drawn to a process for utilizing a viscoushydrocarbon as a combustible fuel for diesel engines as well as acombustible fuel product for diesel engines in the form of a water inhydrocarbon emulsion.

The viscous hydrocarbons employed in the process of the presentinvention include naturally occurring bitumens and residual oilscharacterized by an API gravity of less than or equal to 16° API and aviscosity of greater than or equal to 100 cPs at 122° F. These viscoushydrocarbons in accordance with the present invention are handled fortransportation purposes by forming a hydrocarbon in water emulsion. Inaccordance with the process of the present invention formation of thehydrocarbon in water emulsion employs the use of a non-ionic surfactantas an emulsifier. The hydrocarbon in water emulsion is characterized bya hydrocarbon to water ratio of from about 60:40 to about 90:10,preferably 65:35 to about 75:25. The non-ionic surfactant is required tohave an ethylene oxide content (EO content) of greater than or equal to10 and preferably between about 10 to 100. In accordance with thepresent invention, the non-ionic surfactant is present in the emulsionin an amount of greater than or equal to 2000 ppm. The hydrocarbon inwater emulsion may be formed by any process known in the art. Suitableprocesses are disclosed for example in U.S. Pat. Nos. 4,776,977 and4,934,398 and others discussed above.

In order to obtain a viscous hydrocarbon combustible fuel thehydrocarbon in water emulsion described above must be inverted into awater in hydrocarbon emulsion. In accordance with the present inventiona suitable combustible fuel product for diesel engines comprises a waterin hydrocarbon emulsion wherein the droplet size of the water within theemulsion are within critical values. It has been found that in order toget a more complete combustion at lower temperatures with minimalformations of nitric oxides and soot, the water in hydrocarbon emulsioncombustible fuel for diesel engines should have a mean droplet diameterof less than or equal 4 microns with a maximum water drop diameter ofless than or equal to 10 microns. Such a combustible fuel emulsionproduct having a water to hydrocarbon ratio of 40:60 to about 10:90preferably 35:75 to about 25:75 and a non-ionic surfactant content ofgreater than 2000 ppm and an EO content of preferably between 10 to 100may be effectively atomized at lower temperatures and obtain completecombustion. When the water droplet diameters exceed the critical valuesset forth above, atomization of the fuel becomes incomplete, combustionefficiency is greatly decreased, and elevated temperatures are requiredfor combustion thus resulting in the formation of high amounts of sootand NOX pollutants.

The water in hydrocarbon emulsion fuel product for use as a combustiblefuel in a diesel engine is obtained from the hydrocarbon in wateremulsion formed for transportation of the viscous hydrocarbon bysubjecting the hydrocarbon in water emulsion to a controlled inversionprocess. In accordance with the present invention, the hydrocarbon inwater emulsion is inverted at elevated temperature, that is, greaterthan or equal to 90° C., and critical mixing energies, that is, greaterthan or equal to 6×10⁶ J/m³ so as to invert the emulsion into a water inhydrocarbon emulsion having the required water droplet diameters, bothmean and maximum. The inversion of the emulsion is controlled bycontrolling the temperature and mixing energy during the inversionprocess wherein the temperature is a function of the concentration andEO content of the non-ionic surfactant and the mixing energy is afunction of the hydrocarbon content of the hydrocarbon in wateremulsion. The temperatures required are greater than or equal to 90° C.and mixing energies of greater than or equal to 6.00×10⁶ J/m³. As willbe made clear from the examples hereinbelow, the inversion process is afunction of temperature, mixing energy as well the nature of thenon-ionic surfactant (EO content), the amount of the surfactant in theemulsion, the nature of the viscous hydrocarbon and the hydrocarboncontent.

Advantages of the present invention will be made clear from aconsideration of the following examples.

EXAMPLE 1

Four samples of hydrocarbon in water emulsions where prepared forinversion having a hydrocarbon to water ratio of 70:30 wherein theviscous hydrocarbon had an API gravity of 8.5° and a viscosity of 700cPs at 86° F. The four samples were formed employing a non-ionicsurfactant in a concentration of 3000 ppm and an EO content of 13, 17,33 and 38 respectively. Each of the four samples were heated totemperatures of 80° C., 90° C. and 100° C. and mixed with a mixingenergy of 8.5×10⁶ J/m³. The time required to invert the emulsions andthe resulting water droplet maximum and mean diameters where determined.The results are shown below in Table I.

                  TABLE I                                                         ______________________________________                                        Temp. (°C.)                                                            Surfactant EO                                                                              80          90      100                                          ______________________________________                                        13            22 sec      10 sec  5 sec                                       17           280 sec     200 sec  80 sec                                      33           800 sec     600 sec 250 sec                                      38           1200 sec    800 sec 350 sec                                      Average Drop Dia.                                                             Max          20 μm    10 μm                                                                              6 μm                                      Mean         10 μm    .5 μm                                                                              2 μm                                      ______________________________________                                    

From the foregoing it can be seen that the time for inversion increaseswith EO content and decreases with temperature. The average dropdiameter both max and mean decreases with an increase in temperature.

EXAMPLE 2

Additional emulsions were prepared as in Example 1 wherein the contentof the hydrocarbon was increased to 75:25 and 80:20. The emulsions wereinverted at a temperature of 90° C. and a mixing energy of 8.5×10⁶ J/m³.The results are given in Table II.

                  TABLE II                                                        ______________________________________                                        Hydrocarbon Content (%)                                                       Surfactant EO                                                                              70          75      80                                           ______________________________________                                        13            10 sec      10 sec  4 sec                                       17           200 sec     100 sec 20 sec                                       33           600 sec     100 sec 30 sec                                       38           800 sec     120 sec 35 sec                                       Average Drop Dia.                                                             Max          8 μm     8 μm 6 μm                                      Mean         4 μm     4 μm 2 μm                                      ______________________________________                                    

From Table II it can be seen that as the hydrocarbon content increasesthe time for inversion decreases with a decrease in average dropdiameter both max and mean.

EXAMPLE 3

Emulsions were prepared as in Example 2 except that the surfactantconcentration was reduced to 2000 ppm. The results are shown in TableIII.

                  TABLE III                                                       ______________________________________                                        Temp. (°C.)                                                            Surfactant EO                                                                              80          90      100                                          ______________________________________                                        13            20 sec      10 sec  5 sec                                       17           200 sec     100 sec  60 sec                                      33           500 sec     300 sec 100 sec                                      38           700 sec     400 sec 200 sec                                      Average Drop Dia.                                                             Max          25 μm    8 μm 5 μm                                      Mean         10 μm    4 μm 2 μm                                      ______________________________________                                    

From the foregoing it is clear that inversion time decrease with anddecrease in surfactant concentration as does average drop diameter as afunction of temperature.

EXAMPLE 4

Emulsions were prepared as in Example 1 using a surfactant having an EOcontent of 17. The emulsions were inverted under varying conditions ofelevated temperature and mixing energy. The results are shown in TableIV and Table V.

                  TABLE IV                                                        ______________________________________                                        Mixing Energy (10.sup.6 J/m.sup.3)                                                           3.6    8.5       13.1 15.5                                     ______________________________________                                        Temp °C.                                                               90             800    200       180  120                                      95             400    150       60   40                                       100            320    100       50   10                                       ______________________________________                                    

                  TABLE V                                                         ______________________________________                                        AT TEMP OF 90 °C.                                                                          Average Drop Diameter                                     Mixing Energy (10.sup.6 J/m.sup.3)                                                                Max    Mean                                               ______________________________________                                        3.6                 15     8                                                  8.5                 10     5                                                  13.1                6      3                                                  15.5                5      2                                                  ______________________________________                                    

As can be seen from Tables IV and V, as the mixing energy increases, theaverage drop diameter both max and mean decreases as does inversiontime.

As can be seen from the foregoing, the process of the present inventionallows for the formation of a combustible fuel in the form of a water inhydrocarbon emulsion which allows for utilization of viscoushydrocarbons as combustible fuels in low speed diesel engines.

This invention may be embodied in other forms or carried out in otherways without departing from the spirit or essential characteristicsthereof. The examples described above are therefore considered asillustrative and not restrictive, the scope of the invention beingindicated by the apended claims and all changes which come within themeaning and range of equivalency are intended to be embraced therein.

What is claimed is:
 1. A process for utilizing a viscous hydrocarbon asa combustible fuel for a diesel engine comprising:(a) providing ahydrocarbon in water emulsion having a hydrocarbon to water ratio offrom about 60:40 to about 90:10 and a non-ionic surfactant in an amountof ≧2000 ppm, said hydrocarbon being characterized by an API gravity of≦16° API and a viscosity of ≧100 cPs at 122° F. and said surfactanthaving an ethylene oxide (EO) content of ≧ about 10; (b) subjecting saidhydrocarbon in water emulsion to temperature and mixing energyconditions so as to invert said hydrocarbon in water emulsion into awater in hydrocarbon emulsion characterized by a mean water dropdiameter of ≦4 μm and a maximum drop diameter of ≦10 μm, wherein thetemperature increases with an increase in the EO content of thesurfactant and the mixing energy increases with a decrease in thehydrocarbon content; (c) atomizing said water in hydrocarbon emulsion;and (d) burning the water in hydrocarbon emulsion in a diesel engine. 2.A process according to claim 1 wherein said temperature is ≧90° C. andsaid mixing energy is ≧6.00×10⁶ J/m³.
 3. A process according to claim 1wherein said (EO) content is between about 10 to 100.